Labels & Jumps

label <name> marks a position and jump <name> transfers control to it unconditionally. The pair below is an infinite loop, see the Labels & Jumps Demo.

label loop
println('Hello, world!')
jump loop

Jumps can go forward or backward:

i = 0
label top
i = i + 1
if i < 3
  jump top
endif
println(i)      # 3

Scope

Labels in the main program are visible to the whole main program (including code brought in by import). Labels inside a routine or function are local to it. Jumping to a label in another scope is a compile error (Label 'x' is not defined in global scope).

Stopping the program

halt stops execution immediately:

println('done')
halt
println('never printed')

The program also ends when the last statement has run.